Dubey Gurudutt, Awari Shruti, Singh Tejender, Sahoo Subash C, Bharatam Prasad V
Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar, 160062, Punjab, India.
Department of Chemistry, Panjab University, Sector 14, Chandigarh, 160014, India.
Chempluschem. 2021 Oct;86(10):1416-1420. doi: 10.1002/cplu.202100281.
N-Heterocyclic carbenes, carbocyclic carbenes, remote N-heterocyclic carbenes and N-heterocyclic silylenes are known to form L→N coordination bonds. However, mesoionic carbenes (MICs) are not reported to form coordination bonds with cationic nitrogen. Herein, synthesis and quantum chemical studies were performed on 1,2,3-triazol-5-ylidene stabilized N center. Six compounds with MIC→N ←NHC were synthesized. Density functional theory calculations and energy decomposition analysis were carried out to explore the bonding situation between MIC and N center. The C→N bond lengths were in the range of 1.295-1.342 Å and bond dissociation energies were <400 kcal/mol. Natural bond orbital analysis supported the presence of excess electron density (>3 electrons) at the N center. The computational and X-ray diffraction analysis results confirmed the presence of divalent N character of center nitrogen and MIC→N ←NHC coordination interactions.
已知N-杂环卡宾、碳环卡宾、远程N-杂环卡宾和N-杂环硅烯会形成L→N配位键。然而，尚未有关于中氮茚卡宾（MICs）与阳离子氮形成配位键的报道。在此，对1,2,3-三唑-5-亚基稳定的N中心进行了合成和量子化学研究。合成了六种具有MIC→N ←NHC的化合物。进行了密度泛函理论计算和能量分解分析，以探究MIC与N中心之间的成键情况。C→N键长在1.295 - 1.342 Å范围内，键解离能<400 kcal/mol。自然键轨道分析支持在N中心存在过量电子密度（>3个电子）。计算和X射线衍射分析结果证实了中心氮的二价N特征以及MIC→N ←NHC配位相互作用的存在。
